As with most downloadable software products, items bought in our games (in-app purchases) are non-refundable.
Please change your settings
Restrict children's ability to make in-app purchases, have several layers of options.
You can disable in-app purchases entirely, make it so a password is required for every single in-app purchase, or prevent all purchases entirely by removing the payment method from the account. There's even a way to set up a monthly allowance of iTunes credits.